An antique Belle Epoque natural pearl and diamond negligé pendant, The pendant set with three old-cut diamonds supporting a rare dark brown to black natural pearl and a larger diamond weighing approximately 1.0 ct, G/VVS quality, to a fine chain. Accompanied by a N.E.L. report P5701, dated 5 november 2020, stating the pearl to be natural and of saltwater origin. The natural pearl in this necklace has been described in the Journal of Gemmology, 37 (5), 2021 as an unusual natural pearl from Mytilidae. Due to unusual pigments present and the fact that Mytilidae pearls of this colour and size are rarely encountered, this is a unique pearl. Gross weight 5 grams. Circa 1910